Prior art automatic positioning devices typically moved either the entire object under test on an x-y movable table on which the object rests or utilized a large, movable holder for the x-y movable probe, tool or other like item. X-y movable tables generally are fabricated from precision machined metal plates and castings in order to provide stability and repeatability. As a result, they tend to be large, heavy, costly and slow moving. For a given size test piece, such as a printed circuit board, an x-y table would require an area of about four times the size of the test piece. In the prior art positioning devices wherein the test piece is stationary and a probe, tool or other like item is moved, the probes, tools, etc. generally required a support bracket assembly or fixture which often is several times larger than the size of the probe or tool being held. Because of the mass of the movable bracket assembly or support fixture, quick position changes of the probe cannot be achieved. Due to their size and weight, it is difficult and expensive, and hence impractical to put these prior art automatic positioning devices in a controlled environment chamber, if desired or necessary. Further, if used, the prior art positioning devices would block the view from above of a test piece such as a circuit board under test within the controlled environment test chamber.
To overcome the above difficulties, the present invention was devised.